This invention relates to roller reamer-stabilizer tools useful in the rotary system of earth boring, e.g. for petroleum wells, and more particularly to such tools in which the rollers are provided with integral pins which are rotatably mounted in bearing blocks which are replaceably mounted on the tool body. The invention is equally applicable to reamers and stabilizers, i.e. wall contacting tools, but for simplicity of example will be described with reference to reamers.